Drawing compound



DRAWING COMPOUND Samuel Spring, Philadelphia, and William A. Blum, FortWashington, Pa., assignors to The Pennsylvania Salt ManufacturingCompany, Philadelphia, Pa., a corporation of Pennsylvania No Drawing.Application March 15, 1951, Serial No. 215,858

Claims. 01. 252-17 This invention relates to drawing compounds of thetype used for lubricating and aiding in the art of metal forming.

The compounds of the present invention are particularly well suited foraiding in the drawing of seamless steel tubes which have first receivedan integral phosphate coating. In the art of metal forming, particularlywhere substantial deformations are to be made through the use of dies,it is becoming the practice more and more to first treat the tubes witha phosphating solution to form on the surface of the metal a closelyadherent phosphate coating of a metal such as zinc or iron. The metalwork is then coated with a lubricating composition before being passedthrough the forming dies.

For the drawing of seamless steel tubes, wet lubricants of the soap andfat or soap and fatty-oil type have been found to give good resultsparticularly where the tubes are drawn immediately after coating withthe lubricant. However, lubricants of this type have severalobjectionable features when used for the drawing of tubes in the mannerdescribed. When the tubes are coated with the soap and fat lubricants asnormally used and are not immediately drawn but are stored for severaldays before drawing, it is necessary to recoat the tubes beforesatisfactory drawing can be obtained. This can be overcome by using ahighly concentrated solution of the lubricant. However, this is wastefulof the lubricant and, as a result, is too expensive for satisfactorycommercial operation.

A further objection to the use of. lubricants of the soap and fat typefor drawing metal stock which has first received a phosphate coating isthat the lubricant in the container through which the tubes passsubstantially decreases in viscosity with continued use. As a result,the tubes passing through the low viscosity lubricant do not drag outsufiicient lubricant to give proper lubrication during the drawingoperation. This is particularly true where the tubes being drawn are ofrelatively large diameter. The cause of this decrease in viscosity isnot exactly known but is probably due to the introduction of salts andacids which are still present in small amounts on the treated tubesafter the rinsing of the phosphated stock.

The change in viscosity is readily illustrated by the following: Alubricant containing 4.5% soap, 11.1% fatty material, 0.6% free fattyacid, and 83.8% water had a viscosity of 120 seconds at 150 F. with a#200 Ostwald Fenske viscosimeter before any stock has been immersedtherein, i. e. before use. After using this lubricant for 144 hours, theviscosity of the lubricant was found to have dropped to 23 seconds.

We have discovered that by adding a small amount of starch to lubricantsof the soap and fat type the viscosity of the lubricants is considerablystabilized so that large changes in viscosity on use of the lubricantare avoided. Also, if the starch containing soap and fat lubricant isformulated to have a viscosity of approximately 40 to 120 seconds at 150F. as determined by an-Ostwald Fenske #200 viscosimeter, the lubricatedtubes can be stored for as long as 6 weeks without the necessity ofrelubricating before drawing.

The improvement in storability through the use of small amounts ofstarch is readily apparent from the following example: When using alubricant concentrate analyzing 16% soap, 40% fat, 2% free fatty acid,and 42% water, in order to permit storage for periods over 2 days,without relubrication before drawing, the lubri-, cant must be used inconcentrations of 1 part concentrate to 2 parts water. Substantially thesame lubricant base with the addition of starch analyzing 14.8% soap,37.0% fat, 1.9% free fatty acid, 8% starch and 38.3% water will giveexcellent draws without relubrication after storage of the lubricatedstock for periods in excess of 4 weeks when used in concentrations of 1part concentrate to 5 parts water.

In order to obtain the desired results, the starch must be treated so asto swell its granules. This swelling of the starch granules may beobtained in any suitable manner. The starch may be swollen by heating inwater before addition to the fat-and soap mixture or the unswollenstarch may be added to the fat, soap and water emulsion and the emulsionheated either before or after dilution for use. Also, certain swellingagents may be added which hasten the swelling of the starch granules.Among compounds which act in this manner are borax and sodiumdihydrogen' phosphate.

While various methods may be devised for incorporating the starch withthe soap and fat, we prefer to add the starch as a powder to an emulsionconcentrate of the soap and fat, the concentrate generally being in apasty form. Though the lubricant has been described as being of the soapand fat type, in place of the fat one may use fatty oils, fatty esters,partial fatty esters or mixtures of these. The term fat or fats as usedin this specificationand in the appended claims is intended to includethese somewhat similar materials.

The invention is not limited to any particular soap or fat (the term fatincluding fatty oils, fatty esters, and partial fatty esters), since anyfats or water-dispersible soaps suitable for lubricating purposes may beused in preparing thecompositions of our present invention. Thus, any ofthe water-dispersible soaps obtained from beef tallow, mutton tallow,lard oil, palm oil, etc.; or fatsz beef tallow,mut-ton tallow, lard,degras, etc.; fatty oils: lard oil, palm .oil, cotton seed oil, oliveoil, etc.; or fatty esters: esters of fatty acids with glycerine,sorbitol, ethylene glycol, polyethylene glycol, propylene glycol,diethylene glycol, etc.; or partial fatty esters of fatty acids withglycerine, ethylene glycol, sorbit-ol, polyethylene' glycol may beemployed. We prefer, however, for most purposes to use as the soap atallow soap, and as the fat a tallow treated as by heating with apolyhydric alcohol in the presence of an alkali.

In practicing our invention a pasty compositiomwhich is hereinaftercalled a lubricant concentrate, is preferably first-prepared containing5 to 25 parts soap, 20 to 50 parts fat, 13 to 60 parts water and 4 to 12parts starch. The starch is generally present in an unexpanded orpartially expanded form. The proportion of ingredients should preferablybe' such that after dilution for use, with 3 to 7 parts water per partcomposition and expansion of the starch, as by heating, the viscosity ofthe lubricant emulsion lies between 40 to seconds at F. with a- #200Ostwald Fenske viscosimeter. The starch may be incorporated during theblending of the soap, fat and water 'or may be added to an emulsion ofsoap, fat and water. However, if the latter method is used, the starchshould be thoroughly blended with the emulsion.

In our preferred concentrate compositions the starch is preferablypresent in amounts of 6 to 10 parts starch together with 12 to 16 partssoap, 35 to 42 parts fat, and 32 to 45 parts water. The lubricantconcentrate is diluted 1 part concentrate to 3 .to 7 parts Water beforetreatmentof the stock with the lubricant prior to drawing. In anotherconcentrate system containing bentonite together witha filler, ourpreferred composition contains 4 to 8 parts starch, 10 to 14 parts soap,28 to 35 parts fat, 0.5 to 10 parts bentonite, 10 to 25 parts filler and10 to 45 parts water. These compositions are used in the sameconcentrations as the materials containing no filler.

In order to better illustrate thepractice of our invention, thefollowing examples are given. These examples however, are given for thepurpose of illustration only and should not be consideredin any wayaslimiting the invention thereto.

Example 1 A lubricant concentrate containing 14.8% of a potassium soapof tallow and lard oil, 37.0% tallow, 1.9% free fatty acid (calculatedas oleicacid), 8.0% corn starch and 38.3% water was diluted 1;partconcentrate to parts water at the plant. This diluted lubricant was thenboiled for approximately 3 hours after which time the viscosity onmeasuring was found to be 60 seconds at 150 F. with a #2000stwald Fenskeviscosirneter. The bath was cooled to approximately 150 v1 its usetemperature, and then the tubes to be drawn were immersed in the bathand removed :and stored. The tubes could have been drawn immediately;however, under the operating conditions encountered, the tubes werestored for several days before the actual drawing operation. When drawn,excellent lubrication was obtained.

Example 2 A lubricant containing 5% of a sodium soap of a single pressedstearic acid, 28% tallow, 2% .free fatty acid, potato starch and 55%water was diluted with approximately 5 parts water and boiled until aviscosity was obtained of 60 seconds at 150 F.,'with a #200 OstwaldFenske viscos'imeter, the boiling period being approximately 4 hours.After the lubricant had reached this point, it was cooled toapproximately 130 F. at which temperature it was used for lubricatingstock. The stock lubricated, by immersing, was found to draw easilyafter a weeks storage.

For some particularly difficult drawing operations such, for example, asthe drawing of certain alloy steels, it has been found beneficial toinclude ,withthe starch a small amount of bentonite in the lubricantformulations. The bentonite may be included alone or together withsuitable inert materials such as kaolin, mica, whiting or similar inert.materials. An excellent lubricant suitable for such purposes cal lbeprepared by adding with the starch 2 to 10 parts of bentonite with.orwithout a filler material such as described. ,The'following is anexample of this type of formulation.

Example 3 A lubricant concentrate containing 12.3% soap, 30.0% tallow,1.6% free fatty acid, 4.5% corn starch, 2.4% bentonite, 16.8% kaolin and28.4% water was diluted 1 part concentrate to 4 parts water. The dilutedsolution was boiled for 3 to 4 hours until a viscosity of 58 seconds at150 F. with a #200 -Ostwald "Fenske viscosimeter was obtained. Thislubricant solution was used at a temperature of 150 F. to coat tubesmade of 5% chromium steel which tubes were then stored for a period of 2weeks before drawing. Excellent lubrication was obtained during thedrawing operation.

The lubricant compositions of the present inventionare not to beconfused withthose lubricantcompositions to which starch hasheretoforebeen addedforentirelydifferent purposes. These priorstarch-containingcompositions themselves differ substantially from thesoap, fat

and starch compositions of the present invention. We realize that starchand 'flour'have "heretofore been used as a lubricant for wire drawing.However, the use of starch as a lubricant in the early metal working artdiffers substantially from its use in the present compositions Where thestarch acts more as a modifying agent than as a lubricant itself. We arealso aware of the fact that starch has been used as a binder,particularly in dry lubricants, for giving a firmerbondbetween thelubricant composition and the metal treated. Again the starch in thepresent composition does not serve the purpose of a binder but servesrather to actually modify the lubricant so as to change itscharacteristics by increasing its stability with respect to viscositywhen used and by eliminating the necessity of immediately drawing thework treated. Other materials such as flour, sodium alginate, dextrin,glue, glucose, and proteins such as gelatin, when added to the soap andfat type emulsion lubricant, in place of starch, fail to give'lubricantshaving the desirable characteristics obtainedthrough the use of starch.

Preferably, when metal such as seamless steel tubing is formed throughdrawing operations wherein lubricants of our present invention areemployed, the metal is first cleaned, then immersed in an acid phosphatebath, such as a zinc dihydrogen phosphate bath or an iron phosphate bathto form a phosphate coating thereon. After phosphating, ;the metalisrinsedand then coated with a lubricating solution prepared by adding 3to 7 parts water to a lubricant concentrate of the present invention. Ifthe starch of the concentrate has not been expanded, the lubricantemulsion is also heated, before using, preferably to 180 to 210 'F. for;l to 12 hours, lower temperatures, such as 150 F., being suitable wherelonger periods of heating are used. The tubes can then bedrawnimmediately by passing through the forming dies or can'be stored,without the necessity of further lubrication, for several weeks beforesuch drawing operation.

Though .in describing our present invention the description has beendrawn primarily-to the lubricant concentrates, this being the forminwhich the lubricant compositions would normally be sold, the inventionalso includes the lubricant asactually used in its diluted form. Also,the use of the lubricant composition is not limited to thosedrawingoperations whereinthemetal has been given a phosphate coatingpriortolubrication.

:In describing the invention and particularly in the examples,applicants have described formulations in which specific fats and soapshave been employed and in which the-soaps and fats have been used inspecific proportions. The invention, however, should .not be limited tothese specific ingredients or proportions, nor should the invention belimited to the specific starches disclosed since applicants believe thatany starchesmaybe employed.

Having thusdescribed our invention, we claim:

1. A lubricant composition in-the form of an emulsion comprising 1 to 5parts water-dispersible fatty acid soap, 5 to 12 parts fat,.0.5 to 2parts of expanded starch and to 921parts :water said starch havingbeenexpanded by heating in water for at least one hour at a temperatureof at least F.

2. A lubricant composition prepared by diluting a concentrate comprising5 to 25 parts soap of the group consisting-of sodiumand potassiumlaurate, palmitate, oleate-and stearate, 20 to 50 parts:fat of the groupconsistingof lardoil, palm oil, mutton tallow, beef tallow, l-ardandmixtures. of fatty-acid esters of polyhydric alcohols, 4 to 12 partsstarch and 13 to 60 parts water with 4 to 7 parts water, said starch insaid lubricant having been expanded ;by heating to a temperature of at,least 150 F. for not-less than one hour.

3. .A lubricantcornposition prepared by diluting a concentratecomprising 5 to 25 parts potassium stearate, 20 to 50, parts beeftallow,. 4 to 12 parts starchand 13 1060 parts water with 4-, to 7 Iparts water, said starch in said lubricant having been expanded byheating to a temperature of at least 150 F. for not less than one hour.

4. A lubricant composition prepared by diluting a composition comprisingto 25 parts potassium stearate, 20 to 50 parts of a mixture of fattyacid esters of polyhydric alcohols, 4 to 12 parts starch and 13 to 60parts water with 4 to 7 parts water, said starch in said lubricanthaving been expanded by heating to a temperature of at least 150 F. fornot less than one hour.

5. A lubricant composition prepared by diluting a composition comprising12 to 16 parts potassium stearate, 35 to 42 parts beef tallow, 6 to 10parts of an expanded starch and 32 to 45 parts water with 4 to 7 partswater, said starch in said lubricant having been expanded by heating toa temperature of at least 150 F. for not less than one hour.

6. A lubricant composition prepared by diluting a concentrate comprising5 to 25 parts water-dispersible fatty acid soap, 20 to 50 parts fat, 1to 12 parts starch, 0.5 to 10 parts bentonite and 13 to 60 parts waterwith 4 to 7 parts Water, said starch in said lubricant having beenexpanded by heating to a temperature of at least 150 F. for not lessthan one hour.

7. A lubricant composition prepared by diluting with 4 to 7 parts watera concentrate comprising 10 to 16 parts potassium stearate, 32 to 42parts beef tallow, 4 to 10 parts of an unexpanded starch, 4 to 6 partsbentonite and 30 to 45 parts water said diluted concentrate being heatedto a temperature of at least 150 to 212 F. for not less than one hour toexpand said starch.

8. A lubricant composition prepared by diluting a concentrate comprising5 to 25 parts water-dispersible fatty acid soap, 20 to parts fat, 13 toparts Water and 4 to 12 parts starch, with 4 to 7 parts Water, saidstarch in said lubricant having been expanded by heating to atemperature of at least F. for not less than one hour.

9. The lubricant composition of claim 8 wherein said starch has beenexpanded by heating at a temperature of approximately 212 F. for atleast one hour.

10. In the preparation of metal prior to forming, the step whichcomprises covering the surface of said metal with an emulsion lubricantcomposition of claim 1 at a temperature ofapproximately 150 F. andthereafter letting the lubricant composition cool on said surface.

References Cited in the file of this patent UNITED STATES PATENTS Re.23,184 Whitbeck Dec. 20, 1949 297,606 Kenerson et al. Apr. 29, 18841,781,607 Stamberg Nov. 11, 1930 1,871,939 Adams Aug. 16, 1932 2,040,321Lutz May 12, 1936 2,074,223 Johnson Mar. 16, 1937 2,299,139 Grafton Oct.20, 1942 2,609,594 Whitbeck Sept. 9, 1952 2,609,780 Whitbeck Sept. 9,1952 FOREIGN PATENTS 1,432 Great Britain May 21, 1866

1. A LUBRICANT COMPOSITION IN THE FORM OF AN EMULSION COMPRISING 1 TO 5 PARTS WATER-DISPERSIBLE FATTY ACID SOAP, 5 TO 12 PARTS FAT, 0.5 TO 2 PARTS OF EXPANDED STARCH AND 80 TO 92 PARTS WATER SAID STARCH HAVING BEEN EXPANDED BY HEATING IN WATER FOR AT LEAST ON E HOUR AT A TEMPERATURE OF AT LEAST 150* F. 